/* md2.c
**
** Copyright (c) 2007, Meadhbh S. Hamrick
** All rights reserved.
** 
** Redistribution  and  use  in  source  and  binary  forms,  with  or  without
** modification, are permitted provided that the following conditions are met:
** 
**  * Redistributions of  source code must  retain the above  copyright notice,
**    this list of conditions and the following disclaimer.
** 
**  * Redistributions in binary form must reproduce the above copyright notice,
**    this list of conditions and the following disclaimer in the documentation
**    and/or other materials provided with the distribution.
** 
**  * Neither the  name of  Project Meadhbh  nor the names of  its contributors
**    may be used  to endorse  or promote  products derived from this  software
**    without specific prior written permission.
** 
** THIS SOFTWARE IS PROVIDED BY  THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
** AND ANY  EXPRESS OR IMPLIED WARRANTIES,  INCLUDING, BUT NOT  LIMITED TO, THE
** IMPLIED WARRANTIES  OF MERCHANTABILITY AND FITNESS FOR  A PARTICULAR PURPOSE
** ARE DISCLAIMED.  IN NO  EVENT SHALL THE  COPYRIGHT OWNER OR  CONTRIBUTORS BE
** LIABLE  FOR  ANY  DIRECT,   INDIRECT,  INCIDENTAL,  SPECIAL,  EXEMPLARY,  OR
** CONSEQUENTIAL  DAMAGES  (INCLUDING,  BUT  NOT  LIMITED  TO,  PROCUREMENT  OF
** SUBSTITUTE GOODS  OR SERVICES;  LOSS OF USE,  DATA, OR PROFITS;  OR BUSINESS
** INTERRUPTION)  HOWEVER CAUSED  AND ON  ANY THEORY  OF LIABILITY,  WHETHER IN
** CONTRACT,  STRICT LIABILITY,  OR  TORT (INCLUDING  NEGLIGENCE OR  OTHERWISE)
** ARISING IN ANY WAY  OUT OF THE USE OF THIS SOFTWARE,  EVEN IF ADVISED OF THE
** POSSIBILITY OF SUCH DAMAGE.
** 
** $Id: md2.c 46 2007-08-30 16:52:27Z msh.mobile $
*/

/** \file md2.c
 ** This file implements the MD2 algorithm.
 */

/* Macro Definitions */

/* File Includes */
#include "mutil.h"
#include "mcrypto/md2.h"
#include <stdlib.h>
#include <string.h>

/* Static Prototypes */
static void mc_mic_md2_transform( tMCMd2 *context );
static void mc_mic_md2_checksum( tMCMd2 *context );

/* Static Variables */

static uint8_t mc_mic_md2_pi[256] = {
  0x29, 0x2E, 0x43, 0xC9, 0xA2, 0xD8, 0x7C, 0x01, 0x3D, 0x36, 0x54, 0xA1,
  0xEC, 0xF0, 0x06, 0x13, 0x62, 0xA7, 0x05, 0xF3, 0xC0, 0xC7, 0x73, 0x8C,
  0x98, 0x93, 0x2B, 0xD9, 0xBC, 0x4C, 0x82, 0xCA, 0x1E, 0x9B, 0x57, 0x3C,
  0xFD, 0xD4, 0xE0, 0x16, 0x67, 0x42, 0x6F, 0x18, 0x8A, 0x17, 0xE5, 0x12,
  0xBE, 0x4E, 0xC4, 0xD6, 0xDA, 0x9E, 0xDE, 0x49, 0xA0, 0xFB, 0xF5, 0x8E,
  0xBB, 0x2F, 0xEE, 0x7A, 0xA9, 0x68, 0x79, 0x91, 0x15, 0xB2, 0x07, 0x3F,
  0x94, 0xC2, 0x10, 0x89, 0x0B, 0x22, 0x5F, 0x21, 0x80, 0x7F, 0x5D, 0x9A,
  0x5A, 0x90, 0x32, 0x27, 0x35, 0x3E, 0xCC, 0xE7, 0xBF, 0xF7, 0x97, 0x03,
  0xFF, 0x19, 0x30, 0xB3, 0x48, 0xA5, 0xB5, 0xD1, 0xD7, 0x5E, 0x92, 0x2A,
  0xAC, 0x56, 0xAA, 0xC6, 0x4F, 0xB8, 0x38, 0xD2, 0x96, 0xA4, 0x7D, 0xB6,
  0x76, 0xFC, 0x6B, 0xE2, 0x9C, 0x74, 0x04, 0xF1, 0x45, 0x9D, 0x70, 0x59,
  0x64, 0x71, 0x87, 0x20, 0x86, 0x5B, 0xCF, 0x65, 0xE6, 0x2D, 0xA8, 0x02,
  0x1B, 0x60, 0x25, 0xAD, 0xAE, 0xB0, 0xB9, 0xF6, 0x1C, 0x46, 0x61, 0x69,
  0x34, 0x40, 0x7E, 0x0F, 0x55, 0x47, 0xA3, 0x23, 0xDD, 0x51, 0xAF, 0x3A,
  0xC3, 0x5C, 0xF9, 0xCE, 0xBA, 0xC5, 0xEA, 0x26, 0x2C, 0x53, 0x0D, 0x6E,
  0x85, 0x28, 0x84, 0x09, 0xD3, 0xDF, 0xCD, 0xF4, 0x41, 0x81, 0x4D, 0x52,
  0x6A, 0xDC, 0x37, 0xC8, 0x6C, 0xC1, 0xAB, 0xFA, 0x24, 0xE1, 0x7B, 0x08,
  0x0C, 0xBD, 0xB1, 0x4A, 0x78, 0x88, 0x95, 0x8B, 0xE3, 0x63, 0xE8, 0x6D,
  0xE9, 0xCB, 0xD5, 0xFE, 0x3B, 0x00, 0x1D, 0x39, 0xF2, 0xEF, 0xB7, 0x0E,
  0x66, 0x58, 0xD0, 0xE4, 0xA6, 0x77, 0x72, 0xF8, 0xEB, 0x75, 0x4B, 0x0A,
  0x31, 0x44, 0x50, 0xB4, 0x8F, 0xED, 0x1F, 0x1A, 0xDB, 0x99, 0x8D, 0x33,
  0x9F, 0x11, 0x83, 0x14
};

/* Function Definitions */

/** \fn void mc_mic_md2_clone( tMCMd2 *new_context, tMCMd2 *old_context )
**  \brief clone the state of an MD2 context
*/
void mc_mic_md2_clone( tMCMd2 *new_context, tMCMd2 *old_context ) {
    memcpy( new_context, old_context, sizeof( tMCMd2 ) );
}

/** \fn void mc_mic_md2_clear( tMCMd2 *context )
**  \brief clear sensitive data from the context
*/
void mc_mic_md2_clear( tMCMd2 *context ) {
  return( mc_mic_md2_initialize( context ) );
}

/** \fn void mc_mic_md2_initialize( tMCMd2 *context )
**  \brief initialize a MD2 context to it's initial condition
**  \param context a pointer to a MD2 context data structure
*/
void mc_mic_md2_initialize( tMCMd2 *context ) {
  memset( context, 0, sizeof( tMCMd2 ) );
}
 
/** \fn void mc_mic_md2_update( tMCMd2 *context, uint8_t *data, uint32_t length )
**  \brief provide input to the hash function
**  \param context a pointer to a MD2 context data structure
**  \param data a pointer to the data you want to hash
**  \param length the size of the data you want to hash
*/
void mc_mic_md2_update( tMCMd2 *context, uint8_t *data, uint32_t length ) {
  uint32_t input_index;
  uint32_t block_index;

  for( input_index = 0; input_index < length; input_index ++ ) {
  
    /* add one byte */
    block_index = context->count % 16;
    context->data.asThree.block[ block_index ] = data[ input_index ];

    /* update the counter */
    context->count++;
      
    /* if the block buffer is full, transform the data and checksum */
    if( 15 == block_index ) {
      mc_mic_md2_checksum( context );
      mc_mic_md2_transform( context );
    }
  }
}

/** \fn void mc_mic_md2_digest( tMCMd2 *context, uint8_t *digest )
**  \brief get the digest of the data provided
**  \param context a pointer to a MD2 context data structure
**  \param digest a pointer to where the context will be written
*/
void mc_mic_md2_digest( tMCMd2 *context, uint8_t *digest ) {
  uint32_t i;

  /* Now, pad the block buffer */
  i = 16 - ( context->count % 16 );
  memset( & context->data.asThree.block[ 16 - i ], i, i );

  /* Transform and checksum this block */
  mc_mic_md2_checksum( context );
  mc_mic_md2_transform( context );

  /* Now "append" the checksum and transform once more */
  memcpy( context->data.asThree.block, context->checksum, 16 );
  mc_mic_md2_transform( context );

  /* And copy the state to the "digest" */
  memcpy( digest, & context->data.asThree.state, 16 );
	    
}

static void mc_mic_md2_transform( tMCMd2 *context ) {
  uint32_t i, j, t;
  /* the temp block is initialized to temp[i] = state[i] ^ block[i] */
  for( i = 0; i < 16; i++ ) {
    context->data.asThree.temp[i] =
      context->data.asThree.state[i] ^ context->data.asThree.block[i];
  }

  /* now churn the data */
  for( t = 0, i = 0; i < 18 ; i++ ) {
    for( j = 0; j < 48; j++ ) {
      t = context->data.asOne.x[j] ^= mc_mic_md2_pi[t];
    }
    t = ( t + i ) & 0xFF;
  }

}

static void mc_mic_md2_checksum( tMCMd2 *context ) {
  uint32_t i;
  uint8_t l;

  l = context->checksum[15];
  for( i=0; i<16; i++ ) {
    l = context->checksum[i] ^= mc_mic_md2_pi[ (unsigned int) (context->data.asThree.block[i] ^ l) ];
  }
}

